The use of a tool such as an electric drill, at an overhead position presents special problems. When drilling a hole it is often necessary to first form a pilot hole and then enlarge it with a second drill of larger diameter. If the user is standing on a ladder to form the pilot hole, it is necessary for him to descend the ladder if using a single chuck drill, and then replace the drill bit with one of larger size. The user must then ascend the ladder once again to find the pilot hole to be enlarged. If the pilot hole is not sufficiently deep for the larger drill, the whole process must be repeated.
The need for a tool having two chucks that are interchangeable in position has long been recognized and is the subject of a number of patented proposals. However these proposals have either resulted in a tool that is impracticable to use or which does not allow the user to interchange the positions of the chucks without using both hands. Thus the advantage of having one hand free for some other purpose, such as to hold a ladder the user may be standing on, is lost.
It is therefore an object of the present invention is to provide an improved two-chuck drill.